Wireless access systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless access system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.) among them. For example, multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, and a Single Carrier Frequency Division Multiple Access (SC-FDMA) system.
In particular, in the legacy wireless access systems, a base station or a user equipment performs communication using a half-duplex radio (HDR) scheme such as a frequency division duplex (FDD) scheme for dividing radio resources for signal transmission according to frequency or a time division duplex (TDD) scheme for diving the radio resources according to time.
However, according to the HDR communication scheme, the user equipment and/or the base station cannot simultaneously perform reception and transmission using the same frequency/time resource. Thus, introduction of the FDR communication scheme has been discussed to efficiently use resources. The FDR communication scheme allows the base station and/or the user equipment to simultaneously transmit and receive different signals on the same frequency/time resource region.
In a communication environment using the FDR scheme, since the base station and/or the user equipment simultaneously perform transmission and reception on the same resource region, self-interference, which means that a signal transmitted by a device is received at a reception antenna of the corresponding device, occurs. Hence, methods and apparatuses for cancelling such self-interference are required.